This invention relates to such improvements in divided milling cutters as are generally defined in the preamble of claim 1.
Divided milling cutters of the type to which this invention relates are utilized particularly in the wood working industry, e.g. for tonguing or grooving or alternatively simultaneous round-planing or bevelling of two opposing edges of boards and the like. When boards of another thickness than previously are to be planed, one will have to change the distance between the first (upper) milling cutter half and the second (lower) milling cutter half. A traditional way of carrying out this operation (So called "setting") involves inserting or removing of a greater or smaller number of spacing washers, each having a greater or smaller thickness, between the two cutter halves. This setting operation is tedious and time consuming, since a plurality of bolts have to be unscrewed and tightened again, and it can not be carried out without previous removal of the milling cutter head from the cutter spindle. Another drawback resides therein that the distance adjustment can not be made step-less or continous.
With regard hereto a continously adjustable milling cutter head has been devised long ago, which forms the subject matter of the Swedish Pat. No. 19595. In this prior art device both the lower milling cutter half and the upper cutter half are threaded on to and secured to an externally threaded sleeve by locking nuts. Since the inner cutter half and its locking nut are threaded on from one and the same direction and upon one and the same thread (i.e. not from different directions on to a left-hand thread and a right-hand thread, respectively, which would be most suitable) it is impossible in practice to maintain the initially set distance between the two cutter halves. Furthermore the locking nut of the inner cutter half restricts the minimum distance possible between the cutter halves. In addition hereto resin and other impurities easily get stuck between the halves of the milling cutter, their locking nuts and on the outer thread cooperating therewith.